This invention relates to an electrostatic flocking apparatus which is adapted to flock fibers on one or more surfaces of a workpiece.
A variety of electrostatic flocking apparatus have been proposed and practically employed. One of the prior art electrostatic flocking apparatus generally comprises, in a flocking chamber, an electrode or electrodes to which a high DC voltage is applied by a high DC generator, a box for holding fibers in the form of fine particles to be flocked on a workpiece and a means disposed in opposition to the electrode or electrodes for maintaining the fibers in a grounded condition.
In order to electrostatically flock the fibers on the workpiece by use of the prior art electrostatic flocking apparatus referred to above, the workpiece has a wet adhesive applied on at least one surface thereof and is held by a holding means, and a high DC voltage is applied to the electrode or electrodes with a high DC voltage generator.
Upon the application of voltage to the electrode or electrodes, an electric field is produced between the workpiece and electrode or electrodes and the lines of electric force of the electric field are oriented or directed to the workpiece. The fibers held within the box are charged in the directions of the lines of electric force whereby the fibers are caused to fly towards the workpiece. Since the workpiece has the adhesive applied on at least one surface thereof, the charged fibers penetrate the adhesive on the workpiece to provide a flocked product. The flocked product is then subjected to a drying step to dry the wet adhesive to provide a final flocked product.
However, the above-mentioned electrostatic flocking apparatus presents some problems.
The first problem is that when the charged fibers mix with the non-charged fibers held in the box which is disposed within the filtering chamber, the charged fibers tend to attract some of the non-charged fibers surrounding the charged fibers which do not fly easily. Even if the mass or masses of fibers fly, the fibers will be flocked unevenly on the workpiece resulting in a reject having an unevenly flocked surface or surfaces.
The second problem is that when the fibers fly in a relatively loose condition in the flocking chamber, the fibers may be sparsely flocked on the workpiece.
The third problem is that since the electrostatic flocking is performed by the utilization of the electric field produced between the electrode or electrodes and workpiece as mentioned hereinabove, when the workpiece has a smooth surface or surfaces, the lines of electric forces produced by the electrode or electrodes are uniformly distributed over the workpiece surface or surfaces, but when the workpiece has concave and/or convex surface or surfaces and especially, a recess or recesses as in a so-called deeply drawn moulding having irregular surfaces, the lines of electric force will not be uniformly distributed over the workpiece surface or surfaces. Thus, it is thought that fine flocking cannot be conducted on such a workpiece. In order to finely flock fibers on such a workpiece, it was necessary to employ a special electrode or electrodes adapted to produce lines of electric force which conform with the surface configuration of the workpiece, for example.
In addition to the above-mentioned problems with respect to performance, the prior art electrostatic flocking apparatus has a problem associated with the conveyance of the workpiece.
That is, in order to flock fibers in a predetermined density, it is necessary to cause the workpiece to dwell in the electric field generated within the flocking chamber for a predetermined time period. Thus, in order to efficiently treat a number of workpieces in succession, it is necessary to convey the workpieces in succession into the flocking chamber to have fibers flocked thereon and to convey the treated or flocked workpieces out of the flocking chamber in succession after the completion of the flocking operation to thereby enhance the operation efficiency of the apparatus.
With the aim of enhancing the operation efficiency of the flocking apparatus for electrostatically flocking fibers on a number of workpieces in succession, the conveying mechanism of the prior art flocking apparatus comprises a conveying means in the form of a conveyer or the like which extends from a setting position at which the workpiece is set on a support platform extending through the flocking chamber to a discharge position at which the flocking workpiece is discharged out of the system.
The conveying means is so designed that the workpiece conveyed to the set position in the flocking chamber is caused to dwell in the flocking chamber for a predetermined time period to have fibers flocked thereon and then is conveyed out of the flocking chamber.
However, although the prior art conveying mechanism enhances the operation efficiency of the electrostatic flocking apparatus by conveying the workpieces in succession into and out of the flocking apparatus, since the setting position of the workpiece and the processed workpiece discharge position are separate positions with the flocking chamber interposed therebetween, the flocking apparatus occupies a relatively large space and thus requires the same for the installation thereof.
And, since the flocking chamber is provided with openings in the opposite side walls thereof, a relatively large portion of the fibers filling the flocking chamber tend to disperse out of the chamber through the openings into the environment surrounding the flocking chamber.
Furthermore, when the conveyer is provided within the flocking chamber, it is very difficult to cleam the lower run of the conveyer psoitioned below the workpiece and/or workpiece support platform. Thus, there is the possibility that replacement of the fibers with different fibers is troublesome and/or a portion of the fibers employed in the previous step tend to adhere to a portion of the flocking chamber and mix with the latter fibers to be employed in the succeeding step resulting in the production of a reject.